1. Field of the Invention
This invention relates generally to catheters adapted for sealing and/or occluding cavities and vessels, tubes or other body conduits.
2. Description of the Prior Art
Patients complaining of lower abdominal pain or hematuria (blood in the urine) are often suspect for blockages in the ureter, a relative long, narrow tube which extends from each of the kidneys to the bladder. These blockages may result from kidney stones, tumors, strictures or other obstructions.
The most noninvasive way for determining whether there is a blockage in the ureter is to perform an IV pyleogram. This procedure calls for the intravenous injection of a contrast media or dye into the arm of the patient. This dye eventually collects in the kidneys and passes into the ureters. By using known X-ray fluoroscopic methods, the path of the d ye can be determined. If there is a blockage in the ureter, the path of the dye stops at this blockage providing a contrast in the X-ray which shows the location of the obstruction. If there is more than one obstruction, the dye will be blocked at the first obstruction and may not flow beyond that point. Additional blockages further down the ureter would not be apparent using this intravenous procedure.
Under these conditions, it is sometimes desirable to perform a retrograde procedure which requires that dye be injected at the lower end of the ureter and forced upwardly from the bladder toward the kidney. Although this procedure is quite effective in providing a fluoroscopic view of the lower regions of the ureter, it is somewhat more invasive than the intravenous procedure in that it calls for introduction of an injection catheter through the urethra, into the bladder, and through the ureter orifice into the ureter.
In order to provide suitable visualization of this region, the injection catheter is typically introduced through the working channel of a cystoscope. After the catheter has been positioned, the dye is introduced at the lower end of the ureter and forced upwardly against the force of gravity toward the kidneys. This can present a problem as the dye tends to flow downwardly into the bladder rather than upwardly toward the kidney. In the past, some injection catheters have been provided with enlarged silicone bulbs at their distal ends. These bulbs have been held against the ureter orifice in order to seal the orifice against the downward flow of the dye.
The sealing bulbs have required a size such as fourteen French (14F), a diameter which is sufficient to extend across the normal width of a ureter orifice. While rigid cystoscopes have provided working channels of approximately 14F, the much preferred flexible cystoscopes have working channels of only 7F or 8F. In order to use the injection catheters with the flexible cystoscopes, the catheters have required frontloading, that is they have been introduced through the distal end of the cystoscope toward the proximal end of the cystoscope. After the dye has been injected it is desirable to remove the injection catheter. However, with the relative large seating bulb it has been impossible to withdraw the catheter through the relatviely small working channel of the cystoscope. As a consequence, in order to remove these injection catheters, it had been necessary to remove the entire cystoscope.
What is required is an injection catheter which can be introduced through the narrow channel of a flexible cystoscope, subsequently expanded to block the ureter orifice, and ultimately contracted to permit removal while the cystoscope is left in place.
Catheters of the past have included balloon as well as mesh structures which are expandable from a low profile state. However, the shape of these devices in their expanded state has tended to be round or spherical in cross-section so they have not provided suitable shapes for occluding an orifice. In the case of the mesh structures, the catheters have been adapted solely for embolectomy procedures wherein the expanded mesh structure is used to push blood clots through the vessels. Typically these catheters have not been suitable for injection purposes because the mesh has been porous.
These problems associated with the prior art have been overcome with the present invention which provides a catheter having a tube means adapted for insertion through a body orifice to dispense an injectate into a body conduit or cavity on the other side of the orifice. A mesh tube is provided proximally of the injection port at the end of the catheter tube means. In a particular embodiment this mesh is expandable from approximately 5F to 14F and presents a generally conical surface at its distal end. A suitable silicone can be applied to seal the mesh so that the injectate can flow through the mesh to the injection port at the end of the catheter.
With the injection port positioned in the ureter, the catheter can be moved forward to bring the expanded mesh into contact with the ureter orifice. In this location the expanded mesh forms a seal with the walls of the ureter near the bladder. The seal prevents the injected dye from moving downwardly so that it tends to travel upwardly toward the kidneys.
In one aspect of the invention, the mesh tube has a distal end and a proximal end, and means is provided for the relative movement of the distal end toward the proximal end. This causes the intermediate regions of the tube to expand outwardly thereby providing the tube with an increased diameter and a preferred conical shape. Disposition of the silicone on the tubular mesh can facilitate various other shapes for the mesh in its expanded state.
In a preferred method for making the catheter, a section of the mesh tubing is disposed axially on a mandrel and its ends are bonded to inhibit fraying. The distal end of an injection catheter is moved onto the mandrel in abutting relationship with the mesh subassembly. A tubing sleeve can then be glued over the butt joint between the catheter and the tube. With the mandrel still in place, a coating of silicone can be applied over the mesh to seal the expandable structure. The mandrel is ultimately removed to clear the injection channel which extends through the catheter and the mesh tube.
Finally a wire, or other tension means, is introduced down the injection channel and crimped around the distal end of the mesh tube. In operation, this wire is pulled proximally within the catheter to draw the distal end of the mesh tube toward the proximal end of the mesh tube. This provides the desired expansion and shape for sealing/occluding an orifice, tube, or cavity.
These and other advantages associated with the instant invention would be more apparent with a discussion of preferred embodiments of the concept in reference to the associated drawings.